title: The LKB1 tumor suppressor as a biomarker in mouse and human tissues.
abstract: Germline mutations in the LKB1 gene (also known as STK11) cause the Peutz-Jeghers Syndrome, and somatic loss of LKB1 has emerged as causal event in a wide range of human malignancies, including melanoma, lung cancer, and cervical cancer. The LKB1 protein is a serine-threonine kinase that phosphorylates AMP-activated protein kinase (AMPK) and other downstream targets. Conditional knockout studies in mouse models have consistently shown that LKB1 loss promotes a highly-metastatic phenotype in diverse tissues, and human studies have demonstrated a strong association between LKB1 inactivation and tumor recurrence. Furthermore, LKB1 deficiency confers sensitivity to distinct classes of anticancer drugs. The ability to reliably identify LKB1-deficient tumors is thus likely to have important prognostic and predictive implications. Previous research studies have employed polyclonal antibodies with limited success, and there is no widely-employed immunohistochemical assay for LKB1. Here we report an assay based on a rabbit monoclonal antibody that can reliably detect endogenous LKB1 protein (and its absence) in mouse and human formalin-fixed, paraffin-embedded tissues. LKB1 protein levels determined through this assay correlated strongly with AMPK phosphorylation both in mouse and human tumors, and with mRNA levels in human tumors. Our studies fully validate this immunohistochemical assay for LKB1 in paraffin-embedded formalin tissue sections. This assay should be broadly useful for research studies employing mouse models and also for the development of human tissue-based assays for LKB1 in diverse clinical settings.
authors.affiliation: Department of Pathology and Simmons Cancer Center, UT Southwestern Medical Center, Dallas, Texas, United States of America.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakada
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Stewart
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Peña
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.forename: Ni
authors.initials: N
authors.lastname: Zhao
authors.forename: Nabeel
authors.initials: N
authors.lastname: Bardeesy
authors.forename: Norman E
authors.initials: NE
authors.lastname: Sharpless
authors.forename: Kwok-Kin
authors.initials: KK
authors.lastname: Wong
authors.forename: D Neil
authors.initials: DN
authors.lastname: Hayes
authors.forename: Diego H
authors.initials: DH
authors.lastname: Castrillon
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*
chemical_list: D015415:Biomarkers; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; C491654:Stk11 protein, mouse; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases